1. Confirmed first-time incomplete virologic suppression during treatment with at least 12 weeks of an ARV regimen consisting of TDF or ABC + FTC or 3TC + NNRTI or PI (TDF as Truvada or individually with FTC, and ABC as Epzicom or individually with 3TC). Confirmed first-time incomplete virologic suppression is defined as an initial plasma HIV-1 RNA response < 400 copies/mL, and subsequent virologic rebound > 400 copies/mL measured at two consecutive times.